Re: [PATCH 0/4] cgroups: show correct file mode

KAMEZAWA Hiroyuki
2009-03-03T01:09:58Z

On Tue, 03 Mar 2009 09:08:23 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:

> Paul Menage wrote:
> > On Sun, Mar 1, 2009 at 6:13 PM, Li Zefan <lizf@cn.fujitsu.com> wrote:
> >> Now a cgroup subsystem can set default file mode of its control files,
> >> so here is a patchset to correct file mode of each subsystem's files.
> >
> > I really think that we should be defaulting this based on whether the
> > control file has read or write handlers.
> >
> > Sure, there are special cases like "tasks" that we'd need to set a
> > manual value for, but most of these patches would be unnecessary.
> >
>
> Those patches are small and trivial, but it's ok for me to do this
> automatically. How about below patch.
>
> Note cpuset.memory_pressure is read-only though it has read handler.
> Since if the read handler is removed, it'll return EINVAL instead of
> the current EACCESS, I think it's better to leave as it is.
>
> =====================
>
> cgroups: show correct file mode
>
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> ---
> include/linux/cgroup.h | 5 +++++
> kernel/cgroup.c | 30 ++++++++++++++++++++++++++++++
> kernel/cpuset.c | 1 +
> 3 files changed, 36 insertions(+)
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 6ad1989..af3c10f 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -258,6 +258,11 @@ struct cftype {
> */
> char name[MAX_CFTYPE_NAME];
> int private;
> + /*
> + * If not 0, file mode is set to this value, otherwise it will
> + * be figured out automatically
> + */
> + int mode;
>
> /*
> * If non-zero, defines the maximum length of string that can
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 379baa3..0b19204 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -1750,6 +1750,33 @@ static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
> return error;
> }
>
> +/**
> + * cgroup_file_mode - deduce file mode of a control file
> + * @cft: the control file in question
> + *
> + * returns cftype->mode if ->mode is not 0
> + * returns 0644 if it has both a read and a write handler
> + * returns 0444 if it has only a read handler
> + * returns 0200 if it has only a write hander
> + */
> +static int cgroup_file_mode(const struct cftype *cft)
> +{
> + int mode = 0;
> +
> + if (cft->mode)
> + return cft->mode;
> +
> + if (cft->read || cft->read_u64 || cft->read_s64 ||
> + cft->read_map || cft->read_seq_string)
> + mode += 0444;
> +
> + if (cft->write || cft->write_u64 || cft->write_s64 ||
> + cft->write_string || cft->trigger)
> + mode += 0200;
> +

+= is not |=...

Thanks,
-Kame